To repaint farm machinery, you need a compressor that holds the spray gun's flow for the whole job, and dry, filtered air. A spray gun uses around 350 l/min continuously: with surface preparation and a blow gun, a 1.1 m³/min 4-in-1 screw compressor such as the K 75 covers one paint station, and the K 110 a workshop that paints and repairs at the same time.
In an agricultural machinery workshop, painting is the most demanding job for air quality. A trailer, a plough or a tractor bonnet means square metres of steel to cover without stopping.
Why painting changes the calculation
An impact wrench runs for a few seconds. A spray gun runs for the whole pass, then the next one. So it is counted at 100%, not at 50% like tools that work in bursts. On a large machine, spraying lasts a long time: the compressor must produce that flow continuously, not just draw it from the receiver.
Common values, as a guide, to check against your spray gun manuals:
- Paint spray gun: around 350 l/min, continuous.
- Primer gun: around 300 l/min, continuous.
- Orbital sander for preparation: around 350 l/min, continuous.
- Dusting blow gun: around 150 l/min, counted at 50%.
The calculation for two cases
One painter, with dusting.
- Spray gun: 350 l/min.
- Blow gun: 150 l/min counted at 50% = 75 l/min.
- Total: 425 l/min. With a 25% margin: about 530 l/min.
One painter and one preparer at the same time.
- Spray gun: 350 l/min.
- Orbital sander: 350 l/min.
- Blow gun: 75 l/min.
- Total: 775 l/min. With the margin: about 970 l/min.
If the workshop's impact wrenches run at the same time, add them in. Our configurator adds it up tool by tool.
Which compressor?
- Paint and preparation station: the K 75. 4-in-1 screw compressor, 1.1 m³/min at 8 bar, 420 L receiver, built-in refrigerated dryer and filtration. It covers both cases above with air that is already dry, and handles long sessions.
- Workshop that paints and repairs at once: the K 110. 1.7 m³/min at 8 bar, 340 L receiver, same built-in air treatment. The spare flow keeps pressure steady at the gun when the impact wrenches are running.
- Occasional touch-ups only: the E 75 HP. Two-stage piston compressor, 1.05 m³/min, 300 L receiver. It is enough to touch up a part or a mudguard, provided you add a dryer and filters. To paint a whole machine, spraying lasts too long for intermittent use: choose a screw compressor.
What air quality for painting?
Water and oil droplets leave craters, bubbles and adhesion faults on steel. Painting needs dry, filtered air.
- A refrigerated dryer after the compressor. It is built into the K series. Our article on which air dryer to choose compares the options.
- Fine filters close to the paint station, not only at the compressor: on a long network, air can pick up contamination again on the way. See our article on fine filters.
- An air class defined with our technicians. Our compressors are oil-lubricated: the air class for your station is set according to ISO 8573-1, depending on the paint you use.
Pitfalls specific to farm machinery
- Tool line and paint line mixed together. A lubricator for impact wrenches fitted upstream of the paint station sends oil into the gun. Keep the two lines separate.
- Dust in the workshop. Blowing out combines and radiators fills the air with straw and fine soil. Paint in a separate area, and protect the compressor intake.
- Cold. In a poorly heated workshop, air cools in the pipes and water condenses after the dryer. Filters at the station and automatic drains then become essential.
- Pressure at the gun. Set it at the base of the gun, with a gauge, to the value in the manual. Too much pressure wastes air and paint.
For an enclosed paint shop with a booth, see our page on compressors for spray booths. For your workshop, list your tools in the configurator or send us a description with a quote request.
For your trade: Compressor for agricultural machinery workshops.